The present invention relates to multiplexed data displays and, more particularly, to a novel multiplexed liquid crystal display utilizing varistor material for control of a multiplicity of display cells.
It is well known that reflective liquid crystal display technology is attractive for fabricating displays of the flat panel type, due to the extremely low power consumption, versatility of format and viewability of the display over a wide range of ambient light conditions. Liquid crystal displays have, however, been characterized by their inability to be multiplexed at a high multiplexing order N. The intrinsic non-linearity in the optical response versus the voltage characteristics of the basic liquid crystal effects has hitherto allowed limited multiplexing, to a multiplexing order N of about ten or, equivalently, with a duty factor D=(1/N) of about 0.1. Thus, groups of up to ten display elements can be multiplexed by activating a particular element for one unit of time in every ten time units, with the intrinsic non-linearity of the liquid crystal material layer itself providing sufficient storage to operate that one display cell for the remaining 90% of the time between energization pulses. Due to this relatively low degree of multiplexing capability, the use of multiplexed liquid crystal displays has generally been limited to displays having a relatively small amount of information content, such as may be found in watches and calculators. For displays with a large amount of information content, such as large matrix displays having a large number of elements, it is known that an external non-linear device should be used to control each display element. Suggested approaches to supply external non-linear control devices has been to provide arrays of thin film transistors or silicon transistors upon a silicon backplate, upon one wall of the display, with one of the transistors associated with each of a multiplicity of display cells forming the entire display member. This approach has been generally unsatisfactory due to serious problems in yield and cost. Accordingly, a large area liquid crystal display providing a high order of multiplexing, typically with 100.ltoreq.N.ltoreq.1,000, is desirable.